She unsuccessfully stood as the Labour Party candidate in the Hillsborough ward of Sheffield City Council in 1998 but was subsequently elected in the Manor ward the following year. She was re-elected in the same ward in 2003, before being elected in the Southey ward until she stood down in 2016.[3][4]

In Parliament, Furniss has served on the Women and Equalities Committee. Since October 2016 she has served as Shadow Minister (Business, Energy and Industrial Strategy) (Steel, Postal Affairs and Consumer Protection).[7]